Starting and controlling apparatus for electric discharge lamps



April 1, J. CAMPBELL 2,418,160

STARTING AND CONTROLLING APPARATUS FOR ELECTRIC DISCHARGE LAMPS FiledDec. 51, 1943 Ifiventor: John H. Campbell, W 6. x

His Attorney.

Patented Apr. 1, 1947 STARTING AND CONTROLLING APPARATUS FOR ELECTRICDISCHARGE LAB PS John H. Campbell, Schene General Electric Com New Yorkctady, N. Y., assignor to pany, a corporation of Application December31, 1943, Serial No. 516,419

9 Claims.

My invention relates to apparatus for starting and controlling electricdischarge devices such as discharge lamps of the fluorescent type. As iswell known, discharge lamps require a higher voltage for starting thanfor their subsequent operation. Such lamps in common use at the presenttime have filamentary electrodes and have apparatus associated therewithby which heating current is passed through the electrodes to heat themto an electron emitting temperature before the starting voltage isapplied thereto. As a result of recent developments in the constructionof such lamp electrodes the lamps may be started without prior heatingof the electrodes, that is, started cold cathode without serious injuryto the electrodes. It is the object of my invention to provide improvedapparatus for producing the voltage necessary to effect the starting ofsuch lamps without preheating their electrodes. A further object of myinvention is to provide apparatus which while effective to start a lampwill also control its subsequent operation with the attendant energylosses reduced to a low value.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

Referring to the drawing, Fig. 1 is a circuit diagram illustrating anembodiment of my invention and Fig. 2 is a like diagram illustrating amodification.

Referring first to Fig. 1, two electric discharge devices I and 2 which,for example, may be 40 watt fluorescent lamps of similar constructioneach having the filamentary or thermionic electrodes 3, are connected tobe operated in parallel from the source of alternating current supply 4.The source may be a 60 cycle, 118 volt lighting circuit and theconnection therewith is shown controlled by the line switch 5. Connectedbetween the lamp circuits and the source 4 I employ suitable means, suchas the auto-transformer 6, for stepping up the voltage of the source toa somewhat higher value, for example 330 volts. In the circuit of thelamp l is the lamp ballast reactor 8, which for example may have thesame impedance as the reactor 1; thus both lamps are in lagging currentcircuits, their ballasts being inductive.

As mentioned above, the lamps which I employ,

thermionic electrodes, do nothave their electrodes preheated but ratherare started cold cathode. I obtain the voltage necessary so to start thelamps in the parallel connected circuits illustrated by means ofcircuits which shunt the lamps and which include fixed circuit elementswhich circuits I shall now describe. Connected in shunt with the lamp lis the capacitor 9 whose impedance may, for example, be 5300 ohms andthe reactor It which is constructed to saturate at the voltage appliedthereto upon. the closing of the switch 5 and before the lamps start. Inits saturated condition the impedance of that reactor may, for example,be 635 ohms. As soon as the lamps start the reactor l9 desaturates andin its desaturated condition its impedance may, for example, be 1050ohms. Connected in shunt with the lamp 2 is the capacitor ll whoseimpedance may, for example, be the same as that of the capacitor 9 andthe same reactor ill, the latter being common to the two lamp shuntingcircuits. Inasmuch as the circuits of lamps i and 2 are both inductive,I have shown the capacitor 52 whose impedance may, for example, be 530ohms connected across the secondary of the transformer 6 in order toimprove the power factor of the energy drawn from the source of supply.As a result of the circuit which I have shown and have described abovethe voltages applied to the lamps I and 2 are sufiicient to cause themimmediately to break down upon the closing of the switch 5 after whichthey continue to operate on lagging current circuits with but slightenergy loss in the circuits shunting them.

In the modified form of my invention shown by Fig. 2, I have substitutedlike reactors l3 and it for the capacitors 9 and ii of Fig. 1 andsubstituted the capacitor l5 for the reactor is of thatfigure, it beingunderstood that the reactances of the substituted members, although notthe same as the reactances of the members in Fig. 1 for which they aresubstituted, are such that the voltages applied to the lamps when theswitch 5 is closed are sufiicient to cause the lamps to start. Moreoverduring their operation but slight energy loss occurs in the lampshunting circuits.

The reactive members 9, l l and I5 being capacitors and the reactivemembers It, I3 and I4 being reactors will be spoken of for convenienceas having reactances which are opposite in character inasmuch as thereactive voltage which although provided with occurs across a capacitoris opposite to that which occurs across a reactor.

What'I claim as new and desire to secure by Letters Patent oi the UnitedStates is:

1. In combination, a plurality of inductively reactive lamp circuitshaving reactances of like character each arranged to include an electricdischarge lamp having a pair of electrodes, said circuits beingconnected together to be supplied in parallel from a source ofalternating current supply, a reactive circuit connected to shunt eachlamp, the reactance of each shunt circuit being capacitive prior toconduction by said lamps and including a pair of serially connectedreactive impedance elements connected between electrodes of differentlamps and a common reactive impedance element connected between thecommon juncture of the serially connected impedance elements and otherelectrodes of said lamps.

2. In combination, a plurality of inductively reactive lamp circuitseach arranged to include an electric discharge lamp having a pair ofelectrodes, said circuits being connected together to be supplied inparallel from a source of alternating current supply, and meansconnected directly across electrodes of different lamps and including acapacitive circuit connected to shunt each of said lamps, said shuntcircuits including a reactive member common thereto.

3. In combination, a plurality of inductively reactive lamp circuitseach arranged to include an electric discharge lamp trodes, saidcircuits being connected together to having a pair of elecbe supplied inparallel from a source of alternating current supply, and meansconnected across electrodes of difierent lamps and including acapacitive circuit connected to shunt each of said lamps, each of saidshunt circuits including inductive and capacitive reactive members andsaid shunt circuits including a reactive member in common.

4. In combination, a plurality of inductively reactive lamp circuitseach arranged to include an electric discharge lamp having a pair ofelectrodes, said circuits being connected together to be supplied inparallel from a source of alternating current supply, and meansconnected across electrodes of difierent lamps and including acapacitive circuit including a reactor connected to shunt one of saidlamps and a capacitive circuit including the same reactor connected toshunt another of said lamps.

5. In combination, a plurality of inductively reactive lamp circuitseach arranged to include an electric discharge lamp having a pair ofelectrodes, said circuits being connected together to be supplied inparallel from a source of alternating current supply, and meansconnected directly across electrodes of different lamps comprising apair of serially-connected capacitors, one of said capacitors and areactor connected in series across one of said lamps and the othercapacitor and said reactor connected in series across another of saidlamps.

6. In combination, a plurality of inductively reactive lamp circuitseach arranged to include an electric discharge lamp having a pair ofelectrodes, said circuits being connected together to be supplied inparallel from a source of alternating current supply, and meansconnected directly across electrodes of different lamps comprising apair of serially-connected reactors, a capacitive circuit including oneof said reactors and 'a-capacitor connected to shunt one of said lampsand a capacitive circuit including the same capactitor and the other ofsaid reactors connected to shunt another of said lamps.

'7. In combination, a plurality of inductively reactive lamp circuitseach arranged to include an electric discharge lamp having a pair ofelectrodes, said circuits being connected together to be supplied inparallel from a source of alternating current supply, means connecteddirectly across electrodes of different lamps comprising a pair ofserially connected reactors, one of said reactors and a capacitorconnected in series across one of said lamps, and the other reactor andsaid capacitor connected in series across another of 'said lamps.

8. In combination, a plurality of inductively reactive lamp circuitseach arranged to include an electric discharge lamp, said circuits beingconnected together to be supplied in parallel from a source ofalternating current supply, a capacitive circuit including a reactorconnected to shunt one of said lamps and a capacitive circuit includingthe same reactor connected to shunt another of said lamps, said reactorbeing constructed to saturate at the voltage applied thereto before thelamps start and to desaturate after they start.

9. In combination, a plurality of inductively reactive lamp circuitseach arranged to include an electric discharge lamp, said circuits beingconnected together to be supplied in parallel from a source ofalternating current supply, a capacitor and a reactor connected inseries across one of said lamps and a capacitor and said reactorconnected in series across another of said lamps, said reactor beingconstructedto saturate at the voltage applied thereto before the lampsstart and to desaturate after they start.

JOHN H. CAMPBELL.

1 REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

